remove required=False from transcription serializer

arkindex/documents/serializers/ml.py

@@ -219,7 +219,7 @@ class TranscriptionSerializer(serializers.ModelSerializer):
         read_only=True,
         help_text='This field is deprecated; please use the `confidence` field instead.',
     )
-    orientation = EnumField(TextOrientation, required=False)
+    orientation = EnumField(TextOrientation)
 
     class Meta:
         model = Transcription